In image-forming apparatuses such as copy machines and laser beam printers, a heat fixing method is typically employed in the final stage of printing and copying. This heat fixing method is a method for forming an image by allowing a transfer-receiving material, such as a printing sheet to which a toner image has been transferred, to pass between a fuser roller having a heater therein and a pressure roller to thereby melt an unfixed toner by heating and to fix the toner to the transfer-receiving material.
A typically used fuser roller has a structure in which a fluororesin layer is formed on an outer circumferential surface (surface that comes in contact with a transfer-receiving material) of a tubular base formed of a polyimide, metal, or the like either directly or another layer therebetween. A fuser roller in which, for example, a rubber, which is good in terms of elasticity, releasability, abrasion resistance, and the like, is used as the other layer may be referred to as a “fuser sleeve”. During printing, the fuser roller is used inside a tubular base. A heater is provided inside the fuser roller, and heat generated from the heater is conducted to the outer circumferential surface of the fuser roller to heat a toner.
However, the existing fuser roller described above has a problem in that the structure of the printer becomes complicated because a heater needs to be provided in the fuser roller.
In view of this, a self-heating fuser roller has been proposed in which electrically conductive particles are dispersed in a resin layer near a surface of the fuser roller, the resin layer functioning as a resistor capable of generating heat by being supplied with electricity (refer to Japanese Unexamined Patent Application Publication No. 2014-145828).